In the prior art, combination dial dead bolt assemblies for use in doors accessing secured areas are known. Typically, these assemblies include a combination dial arranged on the outside of the door accessing the secured area. A shaft extends through the door to permit the combination dial to operate the lock and dead bolt assembly arranged on the inside of the door. Typically, in closing of the door, depression of the plunger by the strike activates and extends the bolt in the locked position.
These types of lock assemblies include a knob which may retract the dead bolt in a door strike from the inside of the secured area.
In order to prevent manipulation of the combination dial and inadvertent locking of the dead bolt from the outside of the secured area, prior art combination dial lock assemblies include a blocking feature accessible from the inside of the secured area to prevent unauthorized manipulation of the combination dial and locking of the dead bolt from the outside. In use, these devices permit a person in the secured area to block the locking device to lock the dead bolt in a retracted position thus preventing manipulation of the combination dial.
These prior art locking features are integral parts of the combination dial lock assembly.
Disadvantages associated with these prior art devices include the necessity of removal of the entire combination dial lock assembly to service the locking feature or lock if a malfunction occurs. Moreover, since the blocking feature is integrally made a part of the combination dial lock assembly, the combination dial lock assembly components cannot be replaced with other types or makes of combination dial locks since a combination dial lock having the blocking feature to hold the bolt in a retracted position includes special components associated therewith.
Another deficiency in prior art dead bolt assemblies includes occurrence of lockouts wherein the combination lock lever hangs in the up position against the lever stop resulting in binding of the dead bolt and lock malfunction.
As such, a need has developed to provide an improved combination dial dead bolt assembly which overcomes the deficiencies mentioned above in prior art devices.
The present invention provides an improved dead bolt assembly for a combination dial lock assembly which overcomes the disadvantages noted with prior art devices. In particular, the present invention provides a dead bolt assembly which permits locking a dead bolt assembly in a retracted position with the capability of using the inventive dead bolt assembly with different types and manufacture of combination dial lock assemblies. The present invention also includes features that avoid the occurrences of lockouts wherein a combination lock lever is stuck in an up position as a result of a force being applied against a combination lock dead bolt.